[Bteam] BTeam notes: Tue 24 Jan 2012
Geoffrey Krafft
krafft at jlab.org
Thu Jan 26 11:39:29 EST 2012
On 1/26/2012 9:27 AM, Matt Poelker wrote:
> During the long shutdown, John Hansknecht will try to implement an
> idea that will allow us to produce longer laser pulses, which as Mike
> T points out, could improve transmission, reduce prebuncher gradient,
> and eliminate tails, etc.,. Unfortunately, a longer laser pulse will
> not be available during QWeak and the rest of the 6GeV run.
> Matt
>
>
> Todd Satogata wrote:
>> Bteamers,
>>
>> Here are the notes from yesterday's weekly meeting. There was a lot
>> of discussion about the
>> tune time on Thursday that attempted to install a new M56 optics in
>> the injection chicane
>> but eventually was removed. Some issues were found in the model that
>> will be addressed,
>> a LEMI configuration problem was fixed, some optics anomalies (such
>> as the
>> disappearing/reappearing blown dispersion mismatch out of arc 2) need
>> understanding.
>> We learned important things during that tune time, but we will be
>> more efficient if we
>> have more time to plan and double-check for tuning; Yves's summary at
>> the end of what
>> worked and what didn't will be helpful for the planning of the 5-pass
>> spin-up; a plan is
>> being developed that will be discussed and hopefully scheduled by
>> this week's beam
>> studies scheduling meeting on Friday.
>>
>> Alex Bogacz has graciously agreed to chair the BTeam meeting while
>> I'm on travel
>> to SLAC Jan 26-Feb 1 inclusive.
>>
>> -Todd
>>
>>
>> BTeam-2012-01-24
>>
>>
>> 1 Optics on Call Report/Schedule
>>
>> * Rotates at BTeam (10:00 Tuesdays)
>> * Medium-term machine development
>> o DONE Write 5-pass spin-up ATLis (Jay, a11894
>> <https://cebaf.jlab.org/atlis/task/11894>), relies on
>> ARC9 box supply repair (ongoing)
>> * 17 Jan-24 Jan: Vasily/Yves (Outgoing)
>> o SL has still been running few degrees off crest to reduce
>> Compton backgrounds (Jay)
>> o Hall B sensitivity to energy drift of some concern (Tief)
>> o Mon 23 Jan Add M56 optics in injector (Yves/Jay, a11924
>> <https://cebaf.jlab.org/atlis/task/11924>)
>> + Not successful, see Yves's entry at e1661381
>> <https://cebaf.jlab.org/elog/entry/1661381>
>> + HGAP for inj chicane dipoles will be updated; 0L/0R
>> optics plan in the works
>> + 12h of tuning time: what was gained? How are we
>> accountable for that time?
>> # Who owns the process of unscheduled tuning?
>> Optics or plan owner should be focus; PD
>> schedules time
>> # Scheduling for studies <1h later makes things
>> rushed, perhaps hours of inefficiency
>> # OptiM to elegant translation can use better
>> efficiency (at least yesterday)
>> # High sensitivity of Compton halo to 1L02 quad
>> was found at end in current configuration
>> # Now running 2.5 degrees off crest in SL,
>> better than the 6+ degrees over weekend
>> # We're very likely on the edge of something,
>> including scraping, based on large sensitivities
>> # RayTrace would provide optics, may also well
>> provide an aperture check (Tief)
>> # Spot was a lot tighter in 1A with the M56
>> improvement, so we will likely want to use
>> this in Feb
>> # Is a longer laser pulse feasible for 180uA
>> for better injector transmission/Hall B? (Tief)
>> # Alex: Can redesign an M56 optics with a
>> stronger 1L02 quad setting for potentially
>> improved stability
>> # Underlying cause of arc2 dispersion match
>> blown? Was seen in previous week as well
>> (Jay/Spata/Tief)
>> # DONE Jay has changed LEM config file for NL
>> to set 1L02 quad to 521.6 (as of AM Jan 24 2012)
>> # TODO injector rematch with HGAP in 0R dipoles
>> (Michele/Yves, report Feb 02 BTeam)
>> # TODO Address blown arc2 dispersion match
>> during Jan 25 beam studies recovery (Optics)
>> # TODO Planning group for M56:
>> Yves/Jay/Tief/Alicia/Alex/Ed/Geoff/Yuhong
>> * 24 Jan-31 Jan: Ed/Alex (Oncoming)
>> o TODO Readdress injection matching to NL, SL gang phase,
>> Hall C Compton
>> o TODO Restore SL MOMOD after SL on crest, confirm good
>> Hall C Compton rates (Tief/ops)
>> o TODO Diagnose intermittent problems in NL MOMOD (Musson?
>> Tief? Plawski?)
>> * 31 Jan-07 Feb: Yuhong/Geoff
>> o 5-pass spin-up schedule? Mid-February for Hall A, but
>> early Feb for Hall B shift?
>> * 07 Feb-14 Feb: Balsa/Todd
>> * 14 Feb-21 Feb: Fanglei/Mike Spata
>> * 21 Feb-28 Feb: Todd/Jay
>>
>>
>> 2 Measuring Bunch Length using 1A Sync Light Monitor (Tief)
>>
>> * New BTeam elog entry on this procedure: e1661304
>> <https://cebaf.jlab.org/elog/entry/1661304>
>> * Done capturing images from datacube; online bunch length
>> application may be resurrected (Michele/Tief)
>> * Arne believes this will be resurrected when we have pure
>> digital cameras for 12 GeV
>> * TODO Prioritize and projectize for long down (Arne)
>>
>>
>> 3 C100 Status
>>
>> * 26/52/79 Hz signal on 1/4 cryo drive gradient/phase
>> (Suleiman/Spata)
>> * Beam studies rescheduled for Wed 25 Feb
>>
>>
>> 4 Beam Studies Report 18 Jan 2012
>>
>> * Studies scheduled 08:00-20:00 (on time)
>> o a11858 <https://cebaf.jlab.org/atlis/task/11858> 0.0
>> C100: Search for 79 Hz (Parisitic, Suleiman/Spata; strong
>> 52 Hz on 1/4 cryo drive gradient/phase)
>> o No other studies accomplished due to box supply failures,
>> repair
>>
>>
>> 5 Beam Studies Scheduled 25 Jan 2012
>>
>> * TODO Submit ATLis items for desired beam studies for next week
>> (25 Jan)
>> * Same studies as last week based on lost time to box supply failures
>> * Studies scheduled 08:30-20:30
>> o *[X]* ------ 1.0 Optics: Fopts/allsaves
>> o *[X]* a11882 <https://cebaf.jlab.org/atlis/task/11882>
>> 8.0 C100: Stability testing (Hovater, Spata, etc, full
>> gradient on both C100s, 10uA)
>> o *[X]* a11865 <https://cebaf.jlab.org/atlis/task/11865>
>> 1.0 Modeling: RayTrace validation (Bodenstein, Tief)
>> o *[X]* a11885 <https://cebaf.jlab.org/atlis/task/11885>
>> 0.0 PePPo: Modeling (Grames, Contingency)
>> o *[X]* a11849 <https://cebaf.jlab.org/atlis/task/11849>
>> 0.0 Mott: Mott DAQ Test (Suleiman, Contingency)
>> o *[X]* ------ 2.0 Optics: Restoration
>> * TODO Optics should write notes, observations of fopt/etc to
>> Bteam elog
>> o Include pathlength check (pathlength was good Mon day)
>>
>>
>> 6 Next week
>>
>> * Alex Bogacz has graciously agreed to chair while Todd is on travel
>> * Hall B to 5th pass ~ Feb 1?
>>
>>
>> 7 From last week: Evaluate possibilities of Krest during beam
>> restoration (Okay)
>>
>> * Takes more like 4h to run through both linacs to get decent
>> results (Terry)
>> * But Hall C doesn't get good data while Krest is running either
>> (but Hall B can)
>> * Perhaps part of 2h can be a manual touch-up of cresting (15 min
>> total, 2 operators)
>> o TODO Todd has emailed Noel to see if manual touch-up is
>> acceptable weekly retune
>>
>> ------------------------------------------------------------------------
>>
>> _______________________________________________
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>> Bteam at jlab.org
>> https://mailman.jlab.org/mailman/listinfo/bteam
>
>
> --
> Matt Poelker
> Jefferson Lab
> MS Bldg 5A, Rm 500-17
> 12000 Jefferson Ave.,
> Newport News, VA 23606
> poelker at jlab.org
> 757-269-7357 office
> 757-897-9408 cell
>
>
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Not that I want to stop progress, but I would point out that
we are not scheduled to do any 180 muA running to any hall
AFTER the shutdown, and even if we were, my calculations
show that at 500 MHz and 180 muA, the beam charge is
0.36 pC. If some form of "space charge" mechanism is being
invoked that might "get better" with less charge density, I would
need to see a calculation using, e.g., a formula from Rieser to
convince me that
What IS certain is that the larger bunch length will introduce
greater curvature effects in the compression and aberations.
Not a clear improvement to me!
Geoff
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